Pharmaceutical compositions and methods for treating age-related macular degeneration with melatonin analogues

ABSTRACT

Pharmaceutical compositions and methods for treating and/or preventing age-related macular degeneration with melatonin analogues are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Ser. No. 61/073,963 filed onJun. 19, 2008, the contents of which is incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Takeda Pharmaceutical Company, Ltd., a Japanese corporation, and TakedaGlobal Research and Development Co., Inc., a U.S. corporation, areparties to a joint research agreement.

REFERENCE TO ANY “SEQUENCE LISTING” APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

Age-related macular degeneration (“AMD”) is defined by the gradualdestruction of sharp, central vision in older individuals. The maculararea of the retina processes central vision, and is adjacent to theoptic nerve and near the center of the optic axis. AMD occurs in twoforms, dry and wet.

Dry AMD is defined by the gradual loss of retinal pigment epithelial(RPE) and photoreceptor cells in the macula. Drusen, or yellow depositsunder the retina, are often found in people over 60 and represent anearly indication of developing AMD, but do not in and of themselvescause vision loss. Early AMD is defined by several small drusen or lessfrequent medium-sized drusen. Intermediate AMD is defined by moremedium-sized drusen or a few large drusen. At this stage, visualdisturbances may be reported. Advanced dry AMD is defined by loss ofphotoreceptors and supporting cell types in the macula with accompanyingprogressive vision loss.

Wet AMD is less common and is characterized by growth of abnormal bloodvessels beneath the macular epithelium. These vessels are fragile andleak blood and exudates that separate the macular retina from underlyingstructures. Wet AMD advances more quickly than dry AMD. Rather thanblurry vision characteristic of dry AMD, wet AMD is associated with theperception of straight-line grids as wavy especially at their center.The wet form develops in people who initially present with the dry formand is always considered an advanced form of AMD.

Current treatment for dry AMD consists of a regimen of specifichigh-dose anti-oxidants (vitamins C, E, beta carotene), and copper andzinc (National Eye Institute's Age-Related Eye Disease Study [AREDS]formulation) that reduce the risk of progression of intermediate AMD toadvanced AMD. However, this treatment is not indicated for early AMD dueto lack of efficacy. Wet AMD is treated with laser surgery to destroyabnormal vasculature but may not be indicated for most cases. Newabnormal vessels may develop after initial treatment.

Photodynamic therapy is also used to destroy abnormal vessels.

Yet another treatment option is direct injection of the anti-VEGF(vascular endothelial growth factor) antibody fragment ranibizumab(LUCENTIS, Genentech) which is now approved for the treatment of wetAMD. This treatment may slow vision loss and in some cases actuallyimproves vision. However, it requires intravitreal injection andsubsequent monitoring for increases in ocular pressure. Retinaldetachment or infection may occur along with red eye, vitreous floatersand pain. In addition, bevacizumab is currently being used off-label asan intravitreal injection to treat AMD (Costa et al., InvestigativeOphthamology and Visual Science, 47: 4569-4578, 2006).

Melatonin has been shown to control eye pigmentation (i.e., melanin) andthereby regulate the amount of light that can reach the photoreceptors.Melatonin levels produced by the pineal gland are known to decrease withage in humans, as do levels of melanin in retinal pigment epithelialcells (RPE) (Sarna, T., et al., Exp. Eye Res., 76: 89-98, 2003).Melatonin is also synthesized by photoreceptor cells with a circadianrhythm similar to that of the pineal gland (Weichmann. A. F., Exp. EyeRes., 42: 507-527, 1986). The diminution may decrease the protectionfrom oxidative damage afforded to the RPE by melanin. RPE dysfunction,which is thought to follow oxidative damage, is a well-known initiatorof age-related macular degeneration (AMD).

Melatonin has been shown to protect human retinal pigment epithelial(RPE) cells in vitro when added diurnally to RPE cell cultures for threeconsecutive days. This treatment regimen markedly reduced H₂O₂-inducedcell death and mitochondrial DNA damage (Liang. F.-Q., et al., Exp. EyeRes., 78: 1069-1075, 2004). Other studies have shown that melanin itselfprotects the human RPE from light-induced apoptosis (Seagle, B.-L. L.,et al., Proc. Natl. Acad. Sci. U.S.A., 102: 8978-8983, 2005) and thatmelanin free radicals can quench reactive oxygen species (Seagle, B.-L.L., et al., J. Am. Chem. Soc., 127: 11220-11221, 2005). These studiesare of interest because melatonin, and presumably its analogs, can raisethe level of melanin in the RPE.

A case-controlled study of dry and wet AMD has recently shown that 3 mgmelatonin administered daily at bedtime for at least three months mayreduce the extent of retinal pathology over time. Visual acuity remainedstable, and the change in the picture of the fundus was remarkable inthat few of the examined eyes showed either more retinal bleeding orexudates (Yi, C., et al., Ann. N.Y. Acad. Sci., 1057: 384-392, 2005).

Melatonin is available over the counter in the US generally as a 3 mgtablet for relief from insomnia or jetlag, but has never been fullytested for efficacy or safety and therefore is sold as an over thecounter dietary supplement.

Ramelteon is a melatonin analog described in U.S. Pat. No. 6,034,239(hereby incorporated by reference in the entirety), and is currently FDAapproved for marketing in the US for treatment of sleep disorders. Thisnon-addictive compound is available in an 8 mg tablet, and numerous GCPcompliant clinical trials and drug-drug interaction studies have shownthat ramelteon is safe for humans at significant multiples of thetherapeutic dose. Ramelteon, a sleep-promoting agent, is chemicallydesignated as(S)—N-[2-(1,6,7,8-tetrahydro-2H-indeno-[5,4-b]furan-8-yl)ethyl]propionamide,and is a selective melatonin receptor agonist with high affinity formelatonin MT₁/MT₂ receptors. As a sleep aid, ramelteon appears to actmore as a “switch” rather than exhibiting prominent dose-dependentpharmacology.

Melatonin, melatonin analogues and anti-VEGF agents have all beenproposed as useful pharmacological agents for the treatment of glaucoma.Specifically, it has been suggested that melatonin may be useful for thetreatment of glaucoma (Lundmark et al., Exp. Eye Res., 84: 1021-1030,2007; U.S. Pat. No. 4,654,361 and U.S. Patent Application PublicationNo. 2007/0207116): U.S. Pat. No. 6,034,239 indicates that ramelteon isuseful to treat various disorders accompanies by aging, and also thatramelteon may be useful to treat glaucoma; and off-label use of eitherbevacizumab or ranibuzumab to treat glaucoma with positive results hasbeen reported (Ichhpujani et al., Can. J. Ophthamol., 42: 812-815, 2007:Cheng et al., Annals Academy of Medicine, 37: 72-74, 2008: Dunavoelgyiet al., Clinical and Experimental Ophthamology, 35:878-880, 2007).

BRIEF SUMMARY OF THE INVENTION

The present invention teaches pharmaceutical compositions and methodsfor the treatment of age-related macular degeneration in a patient inneed thereof. In particular, the present invention teaches theadministration of ramelteon or its metabolite, for the treatment and/orprevention of AMD in a patient in need thereof. More specifically,patients identified as having AMD or at high risk for developing AMD canbe treated with therapeutic and/or prophylactic amounts of “ramelteonand/or its metabolite” for preventing or inhibiting the progression ofdisease.

Thus the present invention teaches specific formulations of ramelteonand/or its metabolite pharmaceutical compositions suitable foradministration to a patient in need of treatment for AMD, for theprophylactic treatment against AMD, or for the therapeutic and/orprophylactic prevention of advancement of AMD disease in a patient inneed thereof.

The present invention teaches a method for treating and/or preventingage-related macular degeneration in a patient identified as in needthereof, said method comprising identifying a patient in need oftreatment for age-related macular degeneration, and administering atherapeutic amount of ramelteon to said patient.

The present invention teaches a method as above, wherein the patient isidentified via visual examination of the patient's eye.

The present invention teaches a method as above, wherein the patient isidentified via screening according to risk-factor criteria.

The present invention teaches a method as above, wherein saidage-related macular degeneration is the dry form.

The present invention teaches a method as above, wherein saidage-related macular degeneration is the wet form.

The present invention teaches a method as above, wherein saidage-related macular degeneration occurs in one eye.

The present invention teaches a method as above, wherein saidage-related macular degeneration occurs in two eyes.

The present invention teaches a method as above, wherein saidadministration of ramelteon is via an oral dosage form.

The present invention teaches a method as above, wherein saidadministration of ramelteon is via an injectible dosage form.

The present invention further teaches a method wherein saidadministration of ramelteon is via a surface absorbent dosage form.

The present invention teaches wherein said administration of ramelteonis via a skin-patch dosage form.

The present invention teaches wherein said administration of ramelteonis via a liquid, powder, ointment, paste, gel or cream dosage form.

The present invention teaches wherein said ramelteon is administered ina dose of from 1 mg to 1000 mg.

The present invention teaches a method wherein said ramelteon isadministered as an isolated metabolite of ramelteon,(S)—N-[2-[4-hydroxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl]propionamide(hereinafter, sometimes referred to as metabolite 1), in a dose of from1 mg to 1000 mg.

The present invention teaches wherein administration of a therapeuticamount of ramelteon results in a serum concentration of metabolite 1 offrom 1 μg/L to 100 mg/L.

The present invention teaches wherein said ramelteon is administered ina dose once daily.

The present invention teaches wherein said ramelteon is administered inthe evening.

The present invention teaches wherein said ramelteon is administeredprior to sleep.

The present invention also teaches wherein said ramelteon isadministered in a dose twice daily.

The present invention teaches wherein said ramelteon is administered ina dose more than twice daily.

The present invention teaches wherein administration of a therapeuticamount of ramelteon results in a serum concentration of metabolite 1 offrom 1 μg/L to 100 mg/L. The present invention teaches whereinadministration of a therapeutic amount of ramelteon results in a serumconcentration of metabolite 1 of from 1 μg/L to 100 mg/L.

The present invention further teaches a pharmaceutical compositioncomprising a therapeutic amount of ramelteon, and/or a therapeuticamount of an isolated metabolite of ramelteon, metabolite 1, and apharmaceutically acceptable carrier, excipient or diluent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of the amount of cell viability retained aftertreating a glutamate-containing cell culture medium with ramelteon andmetabolite 1 against idebenone, tocopherol and melatonin as described inExample 2.

FIG. 2 is a graph of absorbance when a glutamate-containing cell cultureis treated with varying concentrations of metabolite 1 as described inExample 2.

DETAILED DESCRIPTION OF THE INVENTION

As described above, “ramelteon” is a known compound which is describedin U.S. Pat. No. 6,034,239, and which has the following chemical name:(S)—N-[2-(1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl)ethyl]propionamide.

As described above, the term “metabolite 1” as used in the presentspecification means the metabolite of ramelteon which has the followingchemical name:(S)—N-(2-[4-hydroxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl)propionamide.

Ramelteon and metabolite 1 can be prepared according to or analogouslyto a method described in the above-mentioned U.S. patent. The compoundsare melatonin receptor agonists.

Age-related macular degeneration (AMD) means the pathological conditionof the retina which is characterized by physical changes in the macularregion of the retina and presents with loss of central vision in thepatient.

AMD can be diagnosed by physical direct or indirect examination of theretina to detect and/or identify characteristic physical appearances ofthe macular region of the retina which are not considered normal. Inparticular, the identification of drusen deposits in the case of dryAMD, or abnormal blood vessel formations in the case of wet AMD.

Patients with a propensity for AMD, or an increased risk for AMD can beidentified via selection criteria scored according to risk factors. Theselection criteria include physical factors such as age of patient (theolder, the greater the risk): family history (if yes, then greaterrisk), and occupational or environmental factors such as exposure tobright sunlight (the greater the exposure, the greater the risk):exposure to bright lights (the greater the exposure, the greater therisk).

Ramelteon acts as a melatonin agonists in mammals (e.g., mouse, rat,hamster, rabbit, feline, canine, bovine, sheep, monkey, human, etc.) andis useful as a composition with a binding affinity for melatoninreceptor, especially a composition agonistic towards melatoninreceptors. Metabolite 1 also has a binding affinity for the melatoninreceptor in mammals (e.g., mouse rat, hamster, rabbit, feline, canine,bovine, sheep, monkey, human, etc).

Ramelteon and metabolite 1 can be used for preventing and treating AMD.

Ramelteon has low toxicity and can be administered safely through peroral or parenteral routes (e.g., for local administration, rectaladministration, intravenous administration, etc.), either directly or aspharmaceutical compositions to be mixed with pharmaceutically acceptablecarriers by using known methods, for example, as tablets (includingsugar-coated tablets, film-coated tablets), powders, granules, capsules(including soft capsules), liquids, eye drops, injections,suppositories, sustained release preparations, plasters and also aschewing gum, etc. Administration may be oral, by inhalation, topical,transmucosal, parenteral, intravenous or intraocular.

Pharmacologically acceptable carriers that may be used to produce thepharmaceutical compositions of the present invention include variousorganic or inorganic carrier substances in common use as pharmaceuticalmaterials, including excipients, lubricants, binders, disintegrants,water-soluble polymers and basic inorganic salts for solid preparations:and solvents, dissolution aids, suspending agents, isotonizing agents,buffers and soothing agents for liquid preparations. Other ordinarypharmaceutical additives such as preservatives, antioxidants, coloringagents, sweetening agents, souring agents, bubbling agents andflavorings may also be used as necessary.

Such “excipients” include, for example, lactose, sucrose, D-mannitol,starch, cornstarch, crystalline cellulose, light silicic anhydride andtitanium oxide.

Such “lubricants” include, for example, magnesium stearate, sucrosefatty acid esters, polyethylene glycol, talc and stearic acid.

Such “binders” include, for example, hydroxypropyl cellulose,hydroxypropylmethyl cellulose, crystalline cellulose,polyvinylpyrrolidone, gum arabic powder, gelatin, pullulan andlow-substitutional hydroxypropyl cellulose.

Such “disintegrants” include (1) crosslinked povidone, (2)super-disintegrants such as crosslinked carmellose sodium (FMC-AsahiChemical) and carmellose calcium (Gotoku Yakuhin), (3) carboxymethylstarch sodium (e.g., product of Matsutani Chemical), (4) low-substitutedhydroxypropyl cellulose (e.g., product of Shin-Etsu Chemical), (5)cornstarch, and so forth. Said “crosslinked povidone” may be anycrosslinked polymer having the chemical name 1-ethenyl-2-pyrrolidinonehomopolymer, including polyvinylpyrrolidone (PVPP) and1-vinyl-2-pyrrolidinone homopolymer, and is exemplified by Colidon CL(produced by BASF), Polyplasdon XL (produced by ISP), Polyplasdon XL-10(produced by ISP) and Polyplasdon INF-10 (produced by ISP).

Such “water-soluble polymers” include, for example, ethanol-solublewater-soluble polymers [e.g., cellulose derivatives such ashydroxypropyl cellulose (hereinafter also referred to as HPC),polyvinylpyrrolidone] and ethanol-insoluble water-soluble polymers[e.g., cellulose derivatives such as hydroxypropylmethyl cellulose(hereinafter also referred to as HPMC), methyl cellulose andcarboxymethyl cellulose sodium, sodium polyacrylate, polyvinyl alcohol,sodium alginate, guar gum].

Such “basic inorganic salts” include, for example, basic inorganic saltsof sodium, potassium, magnesium and/or calcium. Preferred are basicinorganic salts of magnesium and/or calcium. More preferred are basicinorganic salts of magnesium. Such basic inorganic salts of sodiuminclude, for example, sodium carbonate, sodium hydrogen carbonate,disodium hydrogenphosphate, etc. Such basic inorganic salts of potassiuminclude, for example, potassium carbonate, potassium hydrogen carbonate,etc. Such basic inorganic salts of magnesium include, for example, heavymagnesium carbonate, magnesium carbonate, magnesium oxide, magnesiumhydroxide, magnesium metasilicate aluminate, magnesium silicate,magnesium aluminate, synthetic hydrotalcite [Mg₆Al₂(OH)₁₆CO₃.4H₂O] andso forth. Among others, preferred is heavy magnesium carbonate,magnesium carbonate, magnesium oxide, magnesium hydroxide, etc. Suchbasic inorganic salts of calcium include, for example, precipitatedcalcium carbonate, calcium hydroxide, etc.

Such “solvents” include, for example, water for injection, alcohol,propylene glycol, macrogol, sesame oil, corn oil and olive oil.

Such “dissolution aids” include, for example, polyethylene glycol,propylene glycol, D-mannitol, benzyl benzoate, ethanol,trisaminomethane, cholesterol, triethanolamine, sodium carbonate andsodium citrate.

Such “suspending agents” include, for example, surfactants such asstearyltriethanolamine, sodium lauryl sulfate, laurylaminopropionicacid, lecithin, benzalkonium chloride, benzethonium chloride andmonostearic glycerol and hydrophilic polymers such as polyvinyl alcohol,polyvinylpyrrolidone, carboxymethyl cellulose sodium, methyl cellulose,hydroxymethyl cellulose, hydroxyethyl cellulose and hydroxypropylcellulose.

Such “isotonizing agents” include, for example, glucose, D-sorbitol,sodium chloride, glycerol and D-mannitol.

Such “buffers” include, for example, buffer solutions of phosphates,acetates, carbonates, citrates etc.

Such “soothing agents” include, for example, benzyl alcohol.

Such “preservatives” include, for example, p-oxybenzoic acid esters,chlorobutanol, benzyl alcohol, phenethyl alcohol, dehydroacetic acid andsorbic acid.

Such “antioxidants” include, for example, sulfites, ascorbic acid andalpha D-tocopherol.

Such “coloring agents” include, for example, food colors such as FoodColor Yellow No. 5. Food Color Red No. 2 and Food Color Blue No. 2; andfood lake colors and red oxide.

Such “sweetening agents” include, for example, saccharin sodium,dipotassium glycyrrhetinate, aspartame, stevia and thaumatin.

Such “souring agents” include, for example, citric acid (citricanhydride), tartaric acid and malic acid.

Such “bubbling agents” include, for example, sodium bicarbonate.

Such “flavorings” may be synthetic substances or naturally occurringsubstances, and include, for example, lemon, lime, orange, menthol andstrawberry.

The content of ramelteon or metabolite 1 is usually about 0.01 to 100%by weight based on a total weight of the composition.

Specifically, the composition comprising ramelteon or metabolite 1 canbe prepared according to or analogously to the method described in U.S.Pat. No. 6,034,239.

Furthermore, ramelteon or metabolite 1 can also be used in combinationwith other drugs such as H1 antagonists, anti-VEGF antibodies, anti-VEGFaptamer. VEGF receptor protein kinase inhibitor, synthetic steroid,vitamin A, vitamin C, vitamin E. β carotene, lutein and zinc. An exampleof an aptamer is pegaptanib sodium. Examples of antibodies includebevacizumab and ranibizumab.

The composition comprises the other drugs are prepared by using knownmethods, for example, as tablets (including sugar-coated tablets,film-coated tablets), powders, granules, capsules (including softcapsules), liquids, injections, suppositories, sustained releasepreparations, plasters and also as chewing gum, etc. The compound may beadministered as an immediate release form, a controlled release form ora sustained release form.

When ramelteon or metabolite 1 is used in combination with the otherdrugs, examples of administration forms include (1) administration of asingle preparation obtained by formulating ramelteon or metabolite 1 andthe other drugs simultaneously. (2) simultaneous administration of twopreparations obtained by formulating ramelteon or metabolite 1 and theother drugs separately, via an identical route, (3) sequential andintermittent administration of two preparations obtained by formulatingramelteon or metabolite 1 and the other drugs separately, via anidentical route, (4) simultaneous administration of two preparationsobtained by formulating ramelteon or metabolite 1 and the other drugsseparately, via different routes, (5) sequential and intermittentadministration oft two preparations obtained by formulating ramelteon ormetabolite 1 and the other drugs separately, via different routes (e.g.administration in the order of ramelteon or metabolite 1 then the otherdrugs, or in the inverse order) and the like. From a viewpoint ofconvenience of patients, preferred is an administration of a singlepreparation obtained by formulating ramelteon or metabolite 1 and theother drugs simultaneously.

The dose of ramelteon or metabolite 1 differs depending on anadministration subject, and administration route. For example, as atherapeutic agent for AMD, the dosage is about 0.0005 to 2 mg/kg bodyweight, preferably about 0.001 to 1 mg/kg body weight, more preferablyabout 0.001 to 0.5 mg/kg body weight in terms of ramelteon or metabolite1 as active ingredient for an adult. Especially, administration of atherapeutic amount of ramelteon results in a serum concentration ofmetabolite 1 of from 1 μg/L to 100 mg/L, preferably from 100 μg/L to 30mg/L. The pharmaceutical composition may be administered once to severaltimes in divided doses per day.

The dosage of the other drugs can be appropriately selected based on aclinically used dose. In addition, the blending ratio of melatoninreceptor agonist and the other drugs can be appropriately selecteddepending on administration subject, administration route, targetdisease, symptom, the other drugs to be used and the like. Usually, theratio may be decided based on the general dose of the other drugs to beused. When the administration subject is human, for example, 0.01-100parts by weight of other drugs is used relative to 1 part by weight oframelteon or metabolite 1.

The present invention will be described in detail through the followingexamples. The examples are intended to illustrate the present invention,but not to limit the scope of the present invention.

Reference Example 1(S)—N-(2-[4-bromo-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl)propionamide

Bromine was added dropwise into a solution of(S)—N-(2-[1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl)propionamide(27.4 g, 0.11 mol) and sodium acetate (10.4 g, 0.13 mol) in methanol(200 mL) with ice-cooling. The mixture was allowed to stir for 1.5 hourswith ice-cooling, which was quenched with sodium hydrogen sulfite andpoured into water, followed by extracting with ethyl acetate. Theextracted solution was washed with water and a saturated aqueoussolution of sodium hydrogencarbonate, which was dried over anhydrousmagnesium sulfate, followed by distilling off the solvent under reducedpressure. The residue was purified by means of silica gel columnchromatography (ethyl acetate: hexane=8:2) to afford the title compound(yield 33.1 g, 93%) as a white powder.

m.p.: 129-131° C. (recrystallized from ethyl acetate/hexane)

NMR (CDCl₃) δ: 1.15 (3H, t, J=7.5 Hz), 1.50-2.39 (4H, m), 2.19 (2H, q,J=7.5 Hz), 2.67-2.98 (2H, m), 3.02-3.42 (5H, m), 4.53-4.78 (2H, m), 5.47(1H, br s), 7.11 (1H, s).

Elemental Analysis for C₁₆H₂₀BrNO₂:

Calcd.: C, 56.82; H, 5.96; N, 4.14; Br, 23.62.

Found: C, 56.84; H, 5.99; N, 4.14; Br, 23.66.

Reference Example 2(S)—N-(2-[4-methoxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl)propionamide

A solution of sodium methoxide (200 mL, 28% solution in methanol) wasadded dropwise into a mixture of(S)—N-(2-[4-bromo-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl)propionamide(5.00 g, 14.8 mmol), copper(I) bromide (2.12 g, 14.8 mmol) and methylacetate (3.29 g, 44.3 mmol). The mixture was refluxed for 5 hours. Themixture was cooled, which was quenched with 1N HCl, followed byextracting with methanol-chloroform. The extracted solution was driedover anhydrous magnesium sulfate, followed by distilling off the solventunder reduced pressure. The residue was purified by means of silica gelcolumn chromatography and recrystallized from ethyl acetate to affordthe title compound (yield 2.58 g, 60%) as a white powder.

NMR (CDCl₃) δ: 1.14 (3H, t, J 7.5 Hz), 1.50-3.40 (13H, m), 3.84 (3H, s),4.50-4.75 (2H, m), 5.43 (1H, br s), 6.63 (1H, s).

Elemental Analysis for C₁₇H₂₃NO₃:

Calcd.: C, 70.56: H, 8.01; N, 4.84.

Found: C, 70.66; H, 8.02; N, 5.04.

Example 1(S)—N-(2-[4-hydroxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]uran-8-yl]ethyl)propionamide

Boron tribromide (6.92 mmol) was added dropwise into a solution of(S)—N-(2-[4-methoxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl)propionamide(1.00 g, 3.46 mmol) in methylene chloride (15 mL) at about −50° C. Themixture was stirred for 2 hours at temperatures ranging from −50 to 0°C. Crushed ice was added and the mixture was stirred for further 2 hoursat room temperature, followed by extracting with methanol-chloroform.The extracted solution was dried over anhydrous magnesium sulfate,followed by distilling off the solvent under reduced pressure. Theresidue was purified by means of silica gel column chromatography (ethylacetate) to afford the title compound (yield 320 mg, 34%) as a whitepowder. This compound is also referred to as metabolite 1.

m.p.: 149-152° C. (recrystallized from ethyl acetate/hexane)

NMR (CDCl₃) δ: 1.14 (3H, t, J=7.7 Hz), 1.52-2.33 (6H, m), 2.65-2.90 (1H,m), 3.05-3.40 (5H, m), 4.50-4.70 (2H, m), 5.11 (1H, s), 5.44 (1H, br s),6.61 (1H, s).

Elemental Analysis for C₁₆H₂₁NO₃:

Calcd.: C, 69.79; H, 7.69: N, 5.09.

Found: C, 69.68: H, 7.67: N, 5.16.

Example 2 Effect Against Glutamate-Induced Cytotoxicity

We used ramelteon and metabolite 1 (as synthesized in Example 1) in thisstudy. Idebenone and vitamine E (α-tocopherol) were purchased from WakoPure Chemical Industries (Osaka. Japan) and used as positive control.All other chemicals were purchased from standard sources.

N18-RE-105 hybrid cells (mouse neuroblastoma clone N18TG-2 X Fisher rat18-day embryonic neural retina) were cultured with Dulbecco's ModifiedEagles Media (DMEM) supplemented with 5% fetal calf serum (FCS), andhypoxanthine, aminopterin, and thymidine at a 37° C. incubator with 5%CO₂. For cytotoxicity studies, cells were plated in 96-well plates at adensity of 5.000 cells per well in 0.1 ml of the above medium. Afterculturing for 24 hr. the medium was removed and replaced with mediumcontaining 10 mM glutamate with or without various concentrations ofcompounds. After 24 hours of incubation, cytotoxicity was quantitated bythe release of the cytosolic enzyme lactate dehydrogenase (LDH) into theculture medium. The percentage of cell viability in the presence of eachof the test compounds was calculated from the following formula: % cellviability in the presence of compound={LDH activity (absorbance at 550nm) in the culture medium with compound plus 10 mM glutamate−LDHactivity in the control culture medium/LDH activity in the culturemedium with 10 mM glutamate−LD11 activity in the control culturemedium}×100.

FIG. 1 shows the effects of compounds on cytotoxicity induced by 10 mMglutamate. Although the cytotoxicity by glutamate was inhibited by thetreatment of metabolite 1, the incubation with melatonin or ramelteondid not affect cell viability. Higher concentrations of metabolite 1significantly protected against glutamate cytotoxicity compared with theglutamate control. Notably the highest concentration of metabolite 1completely prevented the toxicity of glutamate over the basal viability(FIGS. 1 and 2). Idebenone and tocopherol were used as positive controlsto demonstrate that cell viability was increased with addition of thesecompounds in the presence of glutamate. Since cell death is implicatedin age related macular degeneration, the fact that metabolite 1increases cell viability indicates that metabolite 1 will be useful tocounter the effects of age related macular degeneration.

FIG. 2 shows the amount of absorbance when the glutamate-containing cellcultures are treated with varying amounts of metabolite 1. The level ofabsorbance in the presence of no additives is indicated by the whitebar. The solid bar shows the level of absorbance when 10 mM glutamate isadded, but no metabolite 1 is added. An increase in absorbance indicatesa higher amount of cell death. The striped bars show the amount ofabsorbance when varying amounts of metabolite 1 are added to the 10 mMglutamate treated cell culture. The extent that metabolite 1 inhibitscell death caused by glutamate is illustrated in the chart. Overall, thebar chart shows that as the amount of metabolite 1 increases, cell deathis reduced.

1. A method for treating and/or preventing age-related maculardegeneration in a patient identified as in need thereof, wherein saidmethod comprises identifying a patient in need of treatment forage-related macular degeneration, and administering a therapeutic amountof ramelteon to said patient.
 2. The method of claim 1, wherein thepatient is identified by visual examination of the patient's eye.
 3. Themethod of claim 1, wherein the patient is identified by screeningaccording to risk-factor criteria.
 4. The method of claim 1 wherein saidage-related macular degeneration is the dry form.
 5. The method of claim1 wherein said age-related macular degeneration is the wet form.
 6. Themethod of claim 1 wherein said age-related macular degeneration occursin one eye.
 7. The method of claim 1 wherein said age-related maculardegeneration occurs in two eyes.
 8. The method of claim 1 wherein saidadministration of ramelteon is by an oral dosage form.
 9. The method ofclaim 1 wherein said administration of ramelteon is by an injectibledosage form.
 10. The method of claim 1 wherein said administration oframelteon is by a surface absorbent dosage form.
 11. The method of claim10 wherein said administration of ramelteon is by a skin-patch dosageform.
 12. The method of claim 10 wherein said administration oframelteon is by a liquid, powder, ointment, paste, gel or cream dosageform.
 13. The method of claim 1 wherein said ramelteon is administeredin a dose of from 1 mg to 1000 mg.
 14. The method of claim 1 whereinsaid ramelteon is administered in the form of an isolated metabolite oframelteon,(S)—N-[2-[4-hydroxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl]propionamide,is in a dose of from 1 mg to 1000 mg.
 15. The method of claim 1 whereinadministration of a therapeutic amount of ramelteon results in a serumconcentration of(S)—N-[2-[4-hydroxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl]propionamideof from 1 μg/L to 100 mg/L.
 16. The method of claim 1 wherein saidramelteon is administered in a dose once daily.
 17. The method of claim16 wherein said ramelteon is administered in the evening.
 18. The methodof claim 16 wherein said ramelteon is administered prior to sleep. 19.The method of claim 1 wherein said ramelteon is administered in a dosetwice daily.
 20. The method of claim 1 wherein said ramelteon isadministered in a dose more than twice daily.
 21. The method of claim 19wherein administration of a therapeutic amount of ramelteon results in aserum concentration of(S)—N-[2-[4-hydroxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl]propionamideof from 1 μg/L to 100 mg/L.
 22. The method of claim 20 whereinadministration of a therapeutic amount of ramelteon results in a serumconcentration of(S)—N-[2-[4-hydroxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl]propionamideof from 1 μg/L to 100 mg/L.
 23. The method of claim 1 further comprisingadministering photodynamic therapy.
 24. The method of claim 1 furthercomprising administering therapeutic amount of a pharmaceutical agentselected from the group consisting of bevacizumab, ranibizumab,melatonin, pegatanib and combinations thereof.
 25. A method for treatingand/or preventing age-related macular degeneration in a patientidentified as in need thereof, wherein said method comprisesadministering a therapeutic amount of ramelteon to a patient in need oftreatment for age-related macular degeneration.
 26. The method of claim25 wherein said ramelteon is administered in the form of an isolatedmetabolite of ramelteon,(S)—N-[2-[4-hydroxy-1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl]ethyl]propionamide,in a dose of from 1 mg to 1000 mg.
 27. The method of claim 25 furthercomprising administering photodynamic therapy.
 28. The method of claim25 further comprising administering therapeutic amount of apharmaceutical agent selected from the group consisting of bevacizumab,ranibizumab, melatonin, pegatanib sodium and combinations thereof.29.-30. (canceled)